This invention relates generally to the reconstruction of images and more particularly to methods and apparatus for reconstruction of step-and-shoot CT images using partial image data from adjacent scan positions.
Typical multi-slice CT protocols utilize a helical mode for head scans. The advantages of the helical scans are the ability to reconstruct images at arbitrary locations and the elimination of inter-scan delays. The disadvantage of the helical mode, on the other hand, is the production of image artifacts. When the patient table moves during data acquisition, projection interpolation may be performed to estimate projection samples at the reconstruction location. The interpolation process assumes that the patient table location is known for every projection view. In practice, however, due to technical limitations the patient table location may not be known accurately. As a result, certain assumptions may be made relative to the table motion. For example, an assumption that the table moves at a constant speed and the table locations can be directly calculated from its speed and time may be made. However image artifacts may be generated if the table does not index at a constant speed.